The purpose of this contract is to review and edit the content of approximately 30,000 machine-readable records for the Metathesaurus, a vocabulary database which will be a component of the Unified Medical Language System (UMLS). The Metathesaurus records contain information about biomedical concepts and their representations in different biomedical terminologies and classifications. The contractor will: (1) receive the records in machine-readable form; (2) load the records into contractor- supplied software and hardware; (3) review and edit the content of the records according to specific instructions, and (4) deliver and edited records to the Government in hardcopy and in a specified machine-readable form.